The main bearings have are of the angular contact type with offset inner races so that the balls transmit loads from one groove to the other along straight lines at an angle to the axis of the bearing. The angle-contact ball bearings are designed for bearing combined loading (radial-axial loads).
Bearings of this type can bear thrust loads in one direction only. In fact, under the action of a radial load inside the bearing, an axial force is created that must be counterbalanced by an axial force acting in the opposite direction; that is Why these bearings are generally fitted back to back in pairs.
Note
The main bearings supplied can be bearings with bushing (a) or flanged bearings (b) with the bushing integrated in the external ring of the bearing.
To renew the bearings proceed as follows:
Bearings with bushing
Important
On worn engines, the bearing holder may no longer be a tight fit in the crankcase half.
After having removed the bushing, check that the interference fit between the crankcase and the bushing, with bearing fitted, is no less than 0.03 Mm, otherwise, replace the crankcase halves.
Note
Fit the bearings (1) and (18) orienting them so that the side with the "letter" (c) is facing the bushings (2) and (17).
Flanged bearings
Important
On badly worn engines, bearing outer rings may have developed clearance in the crankcase halves - normally, bearing outer rings are interference-fit in the casing.
Check that the interference fit between the crankcase and the bearings (1) and (18) installed, is not less than 0.03 Mm, otherwise, replace the crankcase halves.
Important
After installing new main bearings, shim the crankshaft as described in the paragraph "shimming the shafts" and "reassembly of the crankcase halves" of this section.
Removal of the oil pump
Undo and remove the screws (9) and (10) securing the pump assembly.
Remove the oil pump assembly (1) and extract the o-rings (2) and (4) from the
crankcase half together with two locating
bushes (15).
...
Riding mode customisation
This function customises each riding style.
To access the function it is necessary to view the ""setting" menu", using
buttons (1) "s" or (2) "t" select the "riding
mode" function and press the reset button (3) to enter the following page.
When accessing the function, the three riding modes ...
Reassembly of the crankcase halves
The crankcase halves must be in good condition and perfectly clean. The
mating surfaces must be perfectly flat and free
from burrs.
Overhauling the alternator-side crankcase half
The following parts must be present on the internal side of the crankcase
half:
Gearbox secondary shaft bearin ...